Wireless transmitter



. w.' T. Dl TcHAM WIRELESS TRANSMITTER- I I Filed Dec. 18, 1920 "NIH 8140044105 Wzllz'am [Dita/mm Patented Apr. 24, 1923.

UNITED-STATES WILLIAM THEODORE DITCHAlVI F TWIGKENHAM, ENGLAND, ASSIGNOR 'lO RADIO CORPORATION 6E AMERICA, or NEW YORK, N. Y., A eonronA'rIoN or DELAWARE.

WIRELESS TRANSMITTER.

Application filed December 18, 1920. Serial No. 431,583.

To all whom it may concern:

Be it known that I, WILLIAM THEODORE DrroHAM, a subject of Great Britain, residing at Kildary, Lebanon Park, Twickenham, in the county of Middlesex, England,

have invented certain new and useful II11- provements in Wireless Transmitters, of which the following is a specification accompanied by drawings.

This invention relates to wireless transmitters of the inductively coupled type.

In accordance with this invention I utilize a primary and a secondary circuit in which a portion of the inductance of one of the circuits is extended to affect the other circuit and means is provided for short circuiting the extended portion for the production of signals.

In the diagrams illustrating tion':

, Fig. 1 'showsa circuit in which the induct ance-of the primary oscillating circuit is extended to aifect the secondary circuit.

7 Fig. 2 is a similar view in which the sec- 25 ondary is extended to affect the primary.

Fig. 3 is another modification in which the primary and secondary are both extended to affect each other.

According to one modification of the invention I divide the inductance of the primary oscillatory circuit into two portions and I extend one portion, which only forms a small part of the whole inductance, so that it may inductively affect the secondary or aerial circuit, and I provide a key or switch by means of which this portion may be shortcircuited for the purpose of I signalling, the primary circuit being so arranged as to produce no direct effect on the secondary 0r aerial circuit when the extended portion is shortcircuited.

This arrangement is illustrated by Figure 1 of the accompanying drawing.

V is a valve oscillator and P the primary oscillation circuit, a portion C of the inductance thereof being extended to act inductively upon the aerial A. K is a key by which this portion C can be shortcircuited.

Thus, when the key K is closed the aerial ceases to oscillate and although the frequency of the primary circuit is thereby slightly varied this variation is not imposed upon the aeral, whilst the load upon the generator remains substantially unaltered. The

the invenkey may air blast.

Alternatively, the extended portion may form part of the secondary or aerial circuit and be disposed so as to influence the primary circuit, in which casethe key or switch Wlll be arranged to shortcircuit this extended portion of the aerial circuit. This arrangement is illustrated by Figure 2 in which G is an arc generator and a portion C of the inductance of the aerial is extended so that it is affected by the primary circuit.

Or I may extend portions of both primary and secondary circuitsand bring them into inductive relation arranging keys or switches to shortcircuit simultaneously both of these portions. This arrangement is illustrated by Figure 3 in which a portion C of the inductance of the primary circuit is extended to affect an extended portion C of the inductance of the aerial. The keys K K are arranged to shortcircuit simultaneously the two portions C C Obviously in any of these arrangements auto coupling may take the place of inductive coupling if desired.

The invention is especially applicable to transmitters employing valves or arcs as generators.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is 1. In radio transmitting apparatus, a vacuum tube oscillator, provided with inductance in its output circuit, an antenna having inductance in its circuit, said inductances being so constructed and arranged as to be substantially without eilect on each other, an inductance connected in one of said circuits and located so as to be coupled to said other circuit, and means for shortcircuiting said last named inductance.

2. The combination claimed in claim 1, in which said last named inductance is relatively small compared to the remaining inductance in its circuit, whereby the tube will oscillate at substantially the same frequency, regardless of the position of the short circuiting means. y

3. 111 radio transmitting apparatus, a vacuum tube oscillator provided with inductance in its output circuit, an antenna having inductance in its circuit, said inif necessary be provided with an ductances being so constructed and arranged as to be substantially Without efiect on each other, an inductance connected in said antenna circuit, an inductance connected in 5 said output circuit, said two last named inductances being locatedso as to be coupled to each other, and means for simultaneously short circuiting both said inductances.

4. The combination claimed in claim 3 in Which said last two named inductances are relatively small compared to the remaining inductance of the circuit whereby the tube Will oscillate at substantially the same frequency regardless ofthe positionof-the short circuiting means.

WVILLIAM THEODORE DITCHAM. 

